1. Field of the Invention
The present invention relates to a method for storing and managing information media each having large capacity such as digital video tapes and optical disks and a system for the same. More particularly, the present invention relates to a method for reducing the number of mount/demount operations of such media and improving response performance and throughput and a system for the same.
2. Description of the Related Art
On-line automation of business transactions are now progressing extensively in various fields such as money and bond markets, commodities circulation and manufacturing business. The custody amount or capacity of various data including on-line data is correspondingly increasing at high speed. In view of this, an information medium storage and management system has now become noticeable. This system uses cartridge type magnetic tapes (MTs) which are easily handled, has holding or custody racks, a plurality of recording/reproducing apparatus and handling apparatus for automatic mount/demount operation of MTs.
A cartridge type MT has a storage capacity in the order of 200 megabytes (MB) and generally stores only one file in it. All MT media are stored on holding or custody racks. In operation of the system, when a request for processing a file is issued, the medium containing the file is mounted on a recording/reproducing apparatus by means of a handling apparatus, demounted therefrom after the end of processing, and returned to the holding or custody rack. For the information medium storage and management system using cartridge type MTs, it is important therefore to shorten the time required for medium mount/demount operation and realize high response performance and throughout.
Meanwhile, the memory density of information medium is increasing rapidly. There are known in practice large capacity information media such as used with digital VTRs and optical disks having a memory capacity of several gigabytes (GB) to several tens of gigabytes (GB) which is several tens to several hundreds times as large as that of a cartridge type MT.
The memory capacity of such a large capacity medium is considerably larger than the capacity of one file so that hundreds of files can be stored in one medium. Thus, there is a large possibility that a plurality of computer jobs used the same medium. It often happens therefore that a medium demounted after the end of processing a computer job must be mounted again upon a request for processing another computer job. If the operation scheme applied to a conventional information media automatic custody system using cartridge type MTs is used for such large capacity media, there is a high possibility that the resultant operation is inefficient at high possibility.